A key outcome from CRESCENDO is the increased process realism of the seven participating Earth system models. Key improvements to the models include; (i) inclusion of the effects of nitrogen limitation on terrestrial carbon uptake. (ii) internally consistent treatment of human land use. (iii) an improved treatment of the marine biological carbon pump. (iv) an increased degree of prognostic coupling between emissions of marine and terrestrial natural aerosol and their processing in the atmosphere. (v) a fully interactive treatment of atmospheric chemistry and aerosols. This increased degree of process realism and coupling means the models are able to simulate a larger range of future feedbacks that may occur in the real world. Improved Earth system models result in more reliable future projections across a range of variables, encompassing the physical, chemical and biological facets of the Earth system. Access to more reliable future projections is an important outcome for European policymakers that can help in planning climate change mitigation actions and in developing sound adaptation strategies. This can result in significant, long-term benefits for the European public, including European businesses and the overall socio-economic system.
CRESCENDO coordinated the European contribution to the scenarioMIP activity within CMIP6. This is the main project delivering new future projections into the IPCC 6th Assessment Report (AR6). The report will be the main climate science guide for policymakers over the coming 5 years. The contribution from CRESCENDO represents an important component of this global effort, which has moved the science beyond what was state-of-the-art.
In the field of emergent constraints and weighting of projections, CRESCENDO has moved the science beyond what was state-of-the art. Emergent constraints can help focus model development onto those processes that are key in controlling the future feedback response of ESMs to increasing CO2 emissions. Doing this can lead to models more reliably simulating future feedbacks, resulting in more reliable future projections. Similarly, an improved use of model weighting can mean that for specific topics, for example agricultural change over Europe, an impact modeller will be able to use the weighting approach to maximize selection of the best performing models for the region and variables of interest to their application. This should lead to more reliable downstream activities where ESM projection data is used, for example in climate impacts modelling. In both cases the net result are more reliable future projection data for subsequent downstream activities, with potential socio-economic benefits.
CRESCENDO has helped to advance Earth system model evaluation, through development and release of ESMValTool vn2.0. This tool is used around the world for model evaluation. Version 2.0 is more efficient than earlier versions and includes an array of new diagnostics developed in CRESCENDO and is available to any researcher. These include diagnostics for; terrestrial carbon and nitrogen cycle, marine biological pump, emissions of natural marine and terrestrial aerosols. All these developments indirectly contribute to improved Earth system models around the world, with potential socio-economic benefits.
Our CRESCENDOschools network was a success. We worked with 16 to 18 year old students, helping them to understand more about the science of Earth system modelling. We took part in public science outreach events where we discussed the type of research we do with the public. The ScienceBrief platform
https://sciencebrief.org/(s’ouvre dans une nouvelle fenêtre) provides the public and media with a quick and reliable explanation of key climate science papers. While there are no direct socio-economic benefits from these activities there can potentially be large, non-measurable impacts on public behaviour and political engagement. These indirect impacts should not be underestimated.
